Mitsubishi, the Japanese company that builds the H-2B rocket for Japan’s space agency JAXA, has identified the cause of the dramatic launchpad fire that broke out only about three hours before the launch of their HTV unmanned ISS cargo freighter.
MHI announced Friday that officials believe the fire started near an “exit hole” on the mobile launch platform. Investigators believe the blaze was most likely caused by static electricity, and exacerbated by a flammable oxygen-rich environment inside the mobile launch platform.
Low winds at Tanegashima during the Sept. 10 countdown allowed oxygen vapors to build up at the launch pad in higher concentrations than previous countdowns, officials said. Super-cold oxygen is used as an oxidizer in both stages of the H-2B rocket, and also flows through the first stage’s twin LE-7A main engines during pre-launch “chilldown” conditioning procedures.
“As a result of the investigation, it was confirmed that there was a high possibility that the fire spread due to the static electricity generated by the oxygen dripping from the engine exhaust port during the propellant filling operation, which continued to blow on the heat-resistant material in the exit hole at the movable launch pad,” MHI said in a statement. “We have taken corrective measures and have confirmed normal functioning of the rocket and facility,” MHI said.
They have rescheduled the launch for September 26. Initially they were aiming for September 24, but rescheduled because there might be an orbital conflict between their rocket’s second stage and the launch of a Soyuz to ISS that same day.
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